Television receivers and other display systems use a cathode ray tube having a fluorescent coating deposited on a slightly curved screen inside the tube. In a black and white tube an electron gun directs a beam of electrons toward the screen with the electron beam being scanned over the surface of the screen by vertical and horizontal deflection systems. A control grid varies the amount of current in the beam to vary the brightness of different areas on the screen. In a color tube a trio of beams are each intensity controlled and each beam is directed toward one of three colors of phosphor on the screen. However, in both black and white and in color television the image can be viewed only from the front of the screen, which is opposite from the side of the screen containing the phosphor. Further, the electron gun requires that a cathode ray tube display system be thick. And still further, the display is constructed of a rigid glass to facilitate direction of the electron beam upon the phosphor.
More recent flat panel displays have significantly reduced the thickness of display systems. Liquid Crystal Display (LCD) systems require individually electrically addressable pixels on the display surface which are switched between transparent and opaque states. The pixels gate light generated typically from an electroluminescence light panel in order to generate the display. Such displays require complex circuitry to activate each pixel, and are visible typically from the side opposite to the electroluminescence panel.
U.S. Pat. No. 4,870,485 to Downing; Elizabeth A., et. al., Sep. 26, 1989, entitled: THREE DIMENSIONAL IMAGE GENERATING APPARATUS HAVING A PHOSPHOR CHAMBER, hereby incorporated by reference, describes a three dimensional image generating apparatus having a three dimensional image inside an image chamber. Such a system has been publicly demonstrated. An imaging phosphor distributed through the image chamber is excited by a pair of intersecting laser beams which cause the phosphor to emit visible light and form an image as the intersecting beams move through the image chamber. The imaging phosphor is a rapidly-discharging, high conversion efficiency, electron trapping type which stores energy from a charging energy beam for a very short time, such as a few microseconds. The imaging phosphor releases photons of visible light when energy from a triggering energy beam reaches phosphor containing energy from the charging beam. This triggering results in radiation of visible light from each point where the charging energy beam crosses the triggering energy beam. A first scanning system directs the charging energy beam to scan through a space in the image chamber and a second scanning system directs the triggering energy beam to scan through space in the image chamber. These two energy beams intersect at a series of points in space to produce a three dimensional image inside the image chamber. The energy beams are provided by a pair of lasers with one beam in the infrared region and the other in the blue, green, or ultraviolet portion of the spectrum. However, an electromechanical mirror based beam steering mechanism makes the display bulky, subject to vibration of the display and the glass cube is rigid.
Thus, what is needed is a thin flexible display panel having multi-color light generating pixels which may be viewed from either side of the panel and requires no moving parts to generate the display. Furthermore, what is need is a method and apparatus for controlling the brightness of pixels comprised within such a display.
Pen-link pointing devices are used in many applications to facilitate a user's interface with a computer via the computer display and are currently widely used in hand held personal computers (HPC). Other applications use CRT displays for such an interface. Most pen pointing devices require a means separate from the display to determine the location of the pen or other pointing device relative to the display. In most HPCs, the separate means takes the embodiment of a touch sensitive film placed over the display.
These films add cost to the product and provide an additional opportunity for failure of the device. Flexible LCDs are being produce for additional display applications and further complicates the use of a pointing device in conjunction with the display because touch sensitive film tends to falsely respond to flexing of the display. Furthermore, most current displays, including LCDs and CRTs are fragile and require a clear protective layer, such as a resilient plastic or glass be placed between the display surface and a pen-like pointing device in order to protect the display from damage by the pen-like pointing device. This additional protective layer separates the tip of the pointing device from the display increasing a parallax affect from the perspective of the user. Thus, what is needed is a display and a pen-like pointing device that can be used without additional locating means such as a touch sensitive film, and that reduces parallax when used.
There are many display applications where fault tolerance and high reliability are essential. Such applications include medical, military, aircraft and spacecraft applications where a failure of a display may prove critical or even fatal. The reliability of many systems is improved by adding redundancy, that is duplicating active circuitry wherein redundant circuitry continues operating in event of failure. Redundant display technology is exceedingly difficult to realize in ordinary CRT and LCD applications because of the characteristics of the display technology. Thus, what is needed is a display system having redundant active components capable of continuing operation of the display system in the event of failure of active components of the system.